Move safe_strerror to posix directory and the base namespace

tools/gn/bootstrap/bootstrap.py

 #!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Bootstraps gn.
 
 It is done by first building it manually in a temporary directory, then building
 it with its own BUILD.gn to the final destination.
 """
@@ skipping 229 matching lines @@
   if is_posix:
     static_libraries['base']['sources'].extend([
         'base/base_paths_posix.cc',
         'base/debug/debugger_posix.cc',
         'base/debug/stack_trace_posix.cc',
         'base/files/file_enumerator_posix.cc',
         'base/files/file_posix.cc',
         'base/files/file_util_posix.cc',
         'base/message_loop/message_pump_libevent.cc',
         'base/posix/file_descriptor_shuffle.cc',
+        'base/posix/safe_strerror.cc',
         'base/process/kill_posix.cc',
         'base/process/process_handle_posix.cc',
         'base/process/process_metrics_posix.cc',
         'base/process/process_posix.cc',
-        'base/safe_strerror_posix.cc',
         'base/synchronization/condition_variable_posix.cc',
         'base/synchronization/lock_impl_posix.cc',
         'base/synchronization/waitable_event_posix.cc',
         'base/sys_info_posix.cc',
         'base/threading/platform_thread_internal_posix.cc',
         'base/threading/platform_thread_posix.cc',
         'base/threading/thread_local_posix.cc',
         'base/threading/thread_local_storage_posix.cc',
         'base/threading/worker_pool_posix.cc',
         'base/time/time_posix.cc',
@@ skipping 143 matching lines @@
     cmd.append('-v')
   cmd.append('gn')
   check_call(cmd)
 
   if not options.debug:
     check_call(['strip', os.path.join(build_dir, 'gn')])
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))